The present invention relates to interdigitated back contact (IBC) solar cells. The top three silicon solar cell efficiencies have been achieved by IBC device structures. The IBC solar cell architecture eliminates front grid shadow loss (2-5 absolute % points) and allows much lower contact resistance by permitting larger contact metal coverage with much easier one-sided cell-to-module integration.
Traditionally, IBC devices have been limited to long-diffusion-length silicon wafers for sufficient carrier transport to the emitter and back contact regions spaced 100 μm-1 mm apart. Patterned doping has been accomplished by ion implantation or multistep diffusion processes. However, no IBC solar cell having acceptable quality has been reported using III-V materials, due to the complex processing steps involved with patterned epitaxial growth and the need for closely spaced emitter/back-contact regions in short-diffusion-length III-V materials.
Accordingly, it would be advantageous to provide an improved method of forming IBC solar cells from III-V materials. Potential benefits of forming an IBC cell from III-V materials include increased efficiency through larger current densities (2-10% depending on concentration), lower contact resistance through larger contact areas (allowing higher fill factors at higher concentrations and lower-cost metals), and simpler fabrication cell and module processing steps compared with both-sides-contacted III-V solar cells.